Lubrication systems

ABSTRACT

A gearbox assembly with emergency lubrication system includes a housing with an interior including a lubricant sump. The housing includes a breather port and a visual inspection port. The breather port is sized for at least one of relieving internal pressure or admitting air. The visual inspection port is located to allow visual inspection of a component in an interior of the housing. A transmission is disposed within the interior of the housing in fluid communication with the lubricant sump. An emergency lubricant reservoir is in fluid communication with the transmission through the breather port and/or the visual inspection port. A method of retrofitting a gear box assembly with an emergency lubrication system includes removing plugs from visual inspection ports of a gearbox housing, removing a breather from a breather port of the gearbox housing, and installing jet plugs into the respective visual inspection ports and breather port.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e)to U.S. Provisional Application No. 62/204,128, filed Aug. 12, 2015,which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to transmissions, and more particularlyto lubrication systems for mechanical power transmissions.

2. Description of Related Art

Rotorcraft transmissions commonly include transmission elements likegears and bearings that transmit rotational power through thetransmission. Because these elements can be subject to heating and wearfrom friction while transmitting rotational power, rotorcrafttransmissions typically include lubrication systems for supplyinglubricant to the transmission components. Such lubrication systemsgenerally irrigate the transmission components with a continuous flow oflubricant. This allows the transmission to transmit mechanical powerwhile limiting heat and wear from friction between transmissioncomponents.

In some rotorcraft transmissions, operation under reduced lubricant flowconditions can accelerate transmission component wear. Aircraftcertification bodies like the Federal Aviation Administration (FAA)therefore generally require that rotorcraft transmissions be able tooperate for a minimum period of time with reduced or no lubricantflow—typically for at least thirty (30) minutes—under oil-outconditions. Transmissions may employ various elements to satisfy theserequirements, such as additive injection, lubricant misting,glycol-based cooling, or supplemental lubrication circuits.

Such conventional lubrication methods and lubrication systems havegenerally been considered satisfactory for their intended purpose.However, there is still a need in the art for improved lubricationmethods and lubrication systems. The present disclosure provides asolution for this need.

SUMMARY OF THE INVENTION

A gearbox assembly with emergency lubrication system includes a housingwith an interior including a lubricant sump. The housing includes abreather port and a visual inspection port. The breather port is sizedfor at least one of relieving internal pressure or admitting air. Thevisual inspection port is located to allow visual inspection of acomponent in an interior of the housing. A transmission is disposedwithin the interior of the housing in fluid communication with thelubricant sump. An emergency lubricant reservoir is in fluidcommunication with the transmission through the breather port and/or thevisual inspection port.

In certain embodiments, the gearbox assembly includes lubrication lines.It is contemplated that each lubrication line can connect the emergencylubrication reservoir to a respective one of the breather port or thevisual inspection port. The gearbox assembly can include a lubricantpump operatively connected to the emergency lubricant reservoir. Thebreather port and the visual inspection port can include respective jettubes to direct lubricant to a desired transmission component. Thebreather port can include a breather disposed therein. It iscontemplated that the breather can include annular filter surroundingthe jet tube.

In accordance with certain embodiments, the transmission includes a mainbevel gear mesh and a tail take-off gear mesh. The housing includes asecond visual inspection port having a further respective jet tube. Theemergency lubricant reservoir is in fluid communication with thetransmission through the second visual inspection port and the furtherrespective jet tube. Outlets of the two jet tubes of the visualinspection ports can be oriented toward the main bevel gear mesh and anoutlet of the jet tube of the breather port can be oriented toward thetail take-off gear mesh.

In another aspect, a method of retrofitting a gear box assembly with anemergency lubrication system includes removing plugs from visualinspection ports of a gearbox housing, removing a breather from abreather port of the gearbox housing, and installing jet plugs into therespective visual inspection ports and breather port. Each jet plugincludes a respective jet tube. In certain embodiments, the methodincludes removing nuts and washers from screws of an accessory module ofa gear box assembly. The method can include installing a first emergencylubrication reservoir by mating the screws on the accessory module withholes on a first reservoir mount, and/or it can include installing asecond emergency lubrication reservoir by mating the screws on theaccessory module with holes on a second reservoir mount. The secondemergency lubrication reservoir can include a pump. It is contemplatedthat the method can include securing the first and second emergencylubrication reservoirs onto the accessory module, and/or can includeinstalling lubrication lines between the jet tubes of the breather portand inspection ports to at least one of the first and second emergencylubrication reservoirs.

In accordance with certain embodiments, the method includes wiring an ACpower source to the pump. It is contemplated that the method can includeinstalling a switch operatively connected to the pump, and wiring an ACpower source to the switch, and/or the method can include securing thelubrication lines to the gearbox housing. The method can also includeorienting the jet tubes to point at desired transmission components.

In another aspect, an emergency lubrication system for use with agearbox assembly described above includes a plug having a jet tubeextending therethrough. The plug is sized to seal either the breather orthe visual inspection port. The emergency lubrication system includes alubrication line connected to the jet tube, a switch and a pump. Anemergency lubrication reservoir is in fluid communication with the jettube through the lubrication line such that, when the pump is activated,lubrication flows from the emergency lubrication reservoir through thelubrication line and the jet tube. The system can include a reservoirmount connected to the emergency lubrication reservoir. The reservoirmount operatively connects the emergency lubrication reservoir anaccessory module of the gearbox assembly.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,embodiments thereof will be described in detail herein below withreference to certain figures, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a rotorcraftconstructed in accordance with the present disclosure, schematicallyshowing a gearbox assembly;

FIG. 2 is a side elevation view of the gearbox assembly of FIG. 1,schematically showing the breather port and the visual inspection ports;

FIG. 3 is a plan view of the gearbox assembly of FIG. 1, showing anexemplary embodiment of jet tubes directed toward the main bevel gearmesh;

FIG. 4 is a cross-sectional side elevation view of a portion of thegearbox assembly of FIG. 1, showing an exemplary embodiment of the jettube of the breather directed toward the tail take-off gear mesh;

FIG. 5 is diagram of an embodiment of a method of retrofitting a gearboxassembly with an emergency lubrication system in accordance with anexemplary embodiment of the present disclosure; and

FIG. 6 is a schematic depiction of an embodiment of a field retrofit kitconstructed in accordance with an exemplary embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of a gearboxassembly in accordance with the disclosure is shown in FIG. 1 and isdesignated generally by reference character 100. Other embodiments ofgearbox assemblies, emergency lubrication systems, and methods ofretrofitting gearbox assemblies in accordance with the disclosure, oraspects thereof, are provided in FIGS. 2-6, as will be described. Thesystems and methods described herein can be used in vehicularapplications, such as in aircraft.

Referring now to FIG. 1, an exemplary rotorcraft 10 is shown. Rotorcraft10 includes a main rotor system 12 and an airframe 14. Airframe 14includes a longitudinally extending tail 16 with a tail rotor system 18,at least one engine 20, and a gearbox assembly 100. Engines 20 areoperatively connected to main rotor system 12 and tail rotor system 18through gearbox assembly 100, and are configured to supply rotationalenergy to both main rotor system 12 through a main rotor shaft 24 andtail rotor system 18 through gearbox assembly 100. Although a particularrotorcraft configuration is illustrated and described in the disclosedembodiment, other configurations and/or machines, such as groundvehicles, jet aircraft, turbofan engines, high speed compound rotarywing aircraft with supplemental translational thrust systems, dualcontra-rotating, coaxial rotor system aircraft, turbo-props, tilt-rotorsand tilt-wing aircraft, will also benefit from the present invention.

As shown in FIGS. 2 and 3, gearbox assembly 100 includes a regularoperation lubrication system (not shown) which provides lubrication tothe gearbox assembly 100 during normal operation, and an emergencylubrication system 101 which provides lubrication when the regularoperation lubrication system breaks down or is unable to provide theneeded lubrication. Gearbox assembly 100 has a housing 102 with aninterior 104. A lubricant sump 106 is disposed within a lower region ofhousing 102 relative to gravity when rotorcraft 10 (shown in FIG. 1) isin level flight. A transmission 112 is disposed within interior 104 ofhousing 102 in fluid communication with lubricant sump 106. Housing 102includes a breather port 108 and two visual inspection ports 110.Breather port 108 is a vent in gearbox housing 102 sized to relieveinternal pressure and/or admit air. Visual inspection ports 110 areopenings in the gearbox housing 102, sealed with respective plugs,described below, which can be removed to for visual inspection of thegears and other internal components. Prior to installation of theemergency lubrication system 101, breather port 108 existed in thehousing 102 to allow insertion of a breather, and the visual inspectionports 110 existed in the housing 102 and provided visual access to thetransmission 112 for use during inspection.

Some gearbox assemblies can leak lubricant from cracks that develop inthe gearbox housing, holes resulting from ballistic impact, ormaintenance incidents such as failure to properly reinstall the gearboxdrain plug and/or other lubrication system components. These can resultin lubricant loss while the gearbox is transmitting rotational energy.Some leaks can be relatively slow, leakage requiring between about tenand sixty minutes before lubricant flow from the primary lubricant flowpath may be reduced. Other losses can be relatively rapid, such aspressure side leaks, leakage requiring less than ten minutes beforelubricant flow from the primary lubricant flow path may be reduced. Inthese cases, an emergency lubrication system 101, described below, canbe switched on.

With reference now to FIG. 2, an emergency lubricant reservoir 114 is influid communication with transmission gears 128, 136 and 130 throughmodified breather port 108 and through visual inspection ports 110.Gearbox assembly 100 includes three lubrication lines 116. Onelubrication line 116 connects the emergency lubrication reservoir 114 tobreather port 108. The other two lubrication lines 116 connect emergencylubrication reservoir 114 to respective visual inspection ports 110.Gearbox assembly 100 includes a second emergency lubricant reservoir 118having a pump 120. Second emergency lubricant reservoir 118 is in fluidcommunication with the first emergency lubrication reservoir 114 so asto pump lubricant from the reservoirs 114, 118. Emergency lubricationreservoirs 114 and 118, respectively, are mounted to an accessory module117 through respective first and second reservoir mounts, 119 and 121,respectively. While not required in all aspects, a switch controlled bya controller can control the pump to provide the lubricant. In otheraspects, the controller could selectively control the pump 120 toregulate the flow of lubricant into the housing 102, such as in pulsesor in a constant stream to ensure lubrication reaches the transmissiongears 128, 136 and 130.

As shown in FIG. 3, visual inspection ports 110 include respective plugs111 having jet tubes 122 therein. Jet tubes 122 direct lubricant fromthe emergency lubricant reservoir 114 to desired transmissioncomponents, for example, components highly sensitive to loss oflubricant. Those skilled in the art will readily appreciate that jettubes 122 can be longer than jet tubes 122 found in breather port 108 sothat the lubricant can effectively reach the desired location. Gearboxassembly 100 includes a main bevel gear mesh 126. Main bevel gear mesh126 is at two locations on the underside of main bevel gear 128 wheremain bevel gear 128 meshes with respective main bevel pinions 130 whichtransmit torque from the input quills of respective engines. Outlets 132of jet tubes 122 of visual inspection ports 110 are oriented toward thetwo locations of main bevel gear mesh 126 and their respective bearings.While described in terms of 30 minute operation and exemplary flowrates, it is understood that other flow rates and operation times can beimplemented in other aspects of the invention.

With reference now to FIG. 4, breather port 108 includes a jet tube 122.Breather port 108 includes a modified breather 124 disposed therein.Modified breather 124 includes annular filter 126 surrounding jet tube122. Gearbox assembly 100 includes a tail take-off gear mesh 136 on thetopside of main bevel gear 128. Above main bevel gear 128 is a tailtake-off gear 135 which meshes with tail take-off pinion 138 to formtail take-off gear mesh 136. An outlet 134 of jet tube 122 of breatherport 108 is oriented toward tail take-off gear mesh 136. It iscontemplated that both plugs 111 and modified breather 124 can includeflanges to assist in fail-safe assembly of plugs 111 and modifiedbreather 124 into their respective ports 110 and 108, respectively. Thishelps to ensure that the jet tubes 122 are consistently aligned towardthe desired transmission component.

Those skilled in the art will readily appreciate that by having jettubes at these three locations, the two locations of main bevel mesh 126and the tail take-off mesh 136, emergency oil is provided to threecritical areas that are most sensitive to loss of oil. In accordancewith some embodiments, the oil flow rate is equivalent to the timerequired to operate without oil. For example, if the emergencylubrication reservoirs hold 1 gallon of oil, and the time required tooperate is 30 minutes then the total flow rate to the critical areasmust be 1 gallon/30 min or 0.033 gal./min. If there are three criticallocations for emergency oil jets, then the flow rate for each of thejets is ⅓ the amount, or 0.011 gal./min.

As shown in FIG. 5, a method 200 of retrofitting a gear box assembly,e.g. gear box assembly 100, with an emergency lubrication system, e.g.emergency lubrication system 101, includes removing plugs from visualinspection ports, e.g. visual inspection ports 110, of a gearboxhousing, e.g. a gearbox housing 102, and removing a breather from abreather port, e.g. breather port 108, of the gearbox housing, asindicated by box 202. Method 200 includes installing jet plugs, e.g.plugs 111 and modified breather 124, into the respective visualinspection ports and breather port, as indicated by box 204. The jetplugs include jet tubes, e.g. jet tubes 122. Method 200 includesorienting the jet tubes to point at desired transmission components,e.g. main bevel gear mesh 126 and/or tail take-off gear mesh 136, asindicated by box 206. While described in terms of specific ports, it isunderstood that other ports could have their plugs or breathers removedto the extent such other ports exist on a particular gear box assembly.

With continued reference to FIG. 5, method 200 includes removingfasteners (such as nuts and washers from screws) of an accessory module,e.g. accessory module 117, of the gear box assembly, and installing afirst emergency lubrication reservoir, e.g. first emergency lubricationreservoir 114, by mating the fasteners (e.g. screws) on the accessorymodule with holes on a first reservoir mount, e.g. first reservoir mount119, as indicated by box 208. Method 200 includes installing a secondemergency lubrication reservoir, e.g. second emergency lubricationreservoir 118, by mating the fasteners (e.g. screws) on the accessorymodule with holes on a second reservoir mount, e.g. second reservoirmount 121, as indicated by box 210.

As shown in FIG. 5, method 200 includes securing the first and secondemergency lubrication reservoirs onto the accessory modules andinstalling lubrication lines, e.g. lubrication lines 116, between thejet tubes of the breather port and inspection ports to at least one ofthe first and second emergency lubrication reservoirs, e.g. first andsecond emergency lubrication reservoirs 114, 118, as indicated by box212. Method 200 includes securing the lubrication lines to the gearboxhousing, as indicated by box 214. Method 200 includes providing power toa pump of the second emergency lubrication reservoir (e.g., wiring an ACpower source to pump 120 of second emergency lubrication reservoir 118,installing a switch operatively connected to pump 120, and wiring an ACpower source to the switch) as indicated by box 216.

With reference now to FIG. 6, the emergency lubrication system isdesigned to be a field retrofit kit so that existing gearbox assembliescan be upgraded to meet the new test requirements and last 30 minutesafter loss of oil from a pressurized lubrication line. Retrofit kit 300includes a breather 324 and two plugs 311, each breather 324 and plug311 includes a respective jet tube 322. Kit 300 includes threelubrication lines 316, a switch 315, and two emergency lubricationreservoirs 314 and 318. Emergency lubrication reservoir 318 includes apump 320 built in. It is also contemplated that kit 300 includes firstand second reservoir mounts, 319 and 321.

Embodiments of the gearbox assemblies, emergency lubrication systems,and methods of retrofitting gearbox assemblies described herein canprovide a supply of lubricant sufficient for gearbox operation for morethan thirty (30) minutes under hover power conditions, and longer incertain embodiments, depending on the power requirements, extending theinterval of time between when the primary lubrication flow may no longerbe able to provide sufficient lubricant flow to when operation of thegearbox assembly may be affected, thereby providing compliance with thecertification requirements described above irrespective of how fastlubricant is lost from the gearbox assembly.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for transmissions with superiorproperties including improved reliability during operation in an oil-outcondition. While described in the context of a rotary wing helicopterand FAA requirements, in is understood that aspects of the invention canbe used which meet other requirements, and can be used in other types ofmachinery, including industrial machinery, automobiles, maritimemachinery, locomotives, without restriction. While the apparatus andmethods of the subject disclosure have been shown and described withreference to preferred embodiments, those skilled in the art willreadily appreciate that changes and/or modifications may be made theretowithout departing from the scope of the subject disclosure.

What is claimed is:
 1. A gearbox assembly with emergency lubricationsystem, comprising: a housing with an interior including a lubricantsump, wherein the housing includes a breather port and a visualinspection port, wherein the breather port is sized for at least one ofrelieving internal pressure or admitting air, and wherein the visualinspection port is located to allow visual inspection of a component inan interior of the housing; a transmission disposed within the interiorof the housing in fluid communication with the lubricant sump; and anemergency lubricant reservoir in fluid communication with thetransmission through at least one of the breather port or the visualinspection port.
 2. The gearbox assembly as recited in claim 1, furthercomprising lubrication lines, wherein each lubrication line connects theemergency lubrication reservoir to at least one of the breather port orthe visual inspection port.
 3. The gearbox assembly as recited in claim1, further including a lubricant pump operatively connected to theemergency lubricant reservoir.
 4. The gearbox assembly as recited inclaim 1, wherein the breather port and visual inspection port includerespective jet tubes to direct lubricant to a desired transmissioncomponent.
 5. The gearbox assembly as recited in claim 4, wherein thebreather port includes a breather disposed therein, and wherein thebreather includes annular filter surrounding the jet tube.
 6. Thegearbox assembly as recited in claim 4, wherein the transmissionincludes a main bevel gear mesh and a tail take-off gear mesh, whereinthe housing includes a second visual inspection port having a furtherrespective jet tube, wherein the emergency lubricant reservoir is influid communication with the transmission through the second visualinspection port and the further respective jet tube, and wherein outletsof the two jet tubes of the visual inspection ports are oriented towardthe main bevel gear mesh and an outlet of the jet tube of the breatherport is oriented toward the tail take-off gear mesh.
 7. A method ofretrofitting a gear box assembly with an emergency lubrication system,comprising: removing plugs from visual inspection ports of a gearboxhousing; removing a breather from a breather port of the gearboxhousing; and installing jet plugs into the respective visual inspectionports and breather port, wherein each jet plug includes a respective jettube.
 8. The method as recited in claim 7, further comprising: removingnuts and washers from screws of an accessory module of a gear boxassembly; installing a first emergency lubrication reservoir by matingthe screws on the accessory module with holes on a first reservoirmount; installing a second emergency lubrication reservoir, wherein thesecond emergency lubrication reservoir includes a pump, by mating thescrews on the accessory module with holes on a second reservoir mount;securing the first and second emergency lubrication reservoirs onto theaccessory module; and installing lubrication lines between the jet tubesof the breather port and inspection ports to at least one of the firstand second emergency lubrication reservoirs.
 9. The method as recited inclaim 8, further comprising wiring an AC power source to the pump. 10.The method as recited in claim 8, further comprising installing a switchoperatively connected to the pump, and wiring an AC power source to theswitch.
 11. The method as recited in claim 8, further comprisingsecuring the lubrication lines to the gearbox housing.
 12. The method asrecited in claim 7, further comprising orienting the jet tubes to pointat desired transmission components.
 13. An emergency lubrication systemfor use with a gearbox assembly having a housing with an interiorincluding a lubricant sump, wherein the housing includes a breather portand two visual inspection ports, the breather port being sized for atleast one of relieving internal pressure or admitting air, and thevisual inspection port being located to allow visual inspection of atransmission in an interior of the housing, the emergency lubricationsystem comprising: a plug having a jet tube extending therethrough,wherein the plug is sized to seal either the breather or the visualinspection port; a lubrication line connected to the jet tube; a pump;and an emergency lubrication reservoir in fluid communication with thejet tube through the lubrication line such that, when the pump isactivated, lubrication flows from the emergency lubrication reservoirthrough the lubrication line and the jet tube.
 14. An emergencylubrication system as recited in claim 13, further comprising areservoir mount connected to the emergency lubrication reservoir,wherein the reservoir mount operatively connects the emergencylubrication reservoir an accessory module of the gearbox assembly.